Room occupancy monitoring — data instead of guesswork

Room occupancy monitoring is often confused with a booking system: if the room calendar is full, the office is apparently running at full tilt. Yet every facility manager knows the view from a walk-round — a room blocked for the whole day stands empty, every third zone in the open space is occupied, and the lighting and air conditioning run everywhere. Decisions about floor space — one of a company's biggest fixed costs — are made on the strength of a corridor impression or last year's survey. An occupancy sensor does for this topic what a temperature logger did for the cold room: it turns anecdote into a chart that is hard to argue with.

A booking is not presence

Between what the calendar shows and what happens in the building there is a gap — and that gap is what costs the most:

• Rooms booked "just in case". A recurring meeting nobody has needed for months blocks the best room at peak hours. Without presence measurement nobody can prove it, so nobody cancels it.
• Floor space cut oversized. In hybrid work, the number of desks no longer follows from headcount. The decision "do we lease another floor or densify the current one" needs data on the real occupancy of zones — day by day, hour by hour.
• Energy in empty rooms. Lighting and ventilation running in rooms where nobody has been for three hours is the most predictable loss line in an office building.
• Servicing "evenly". Cleaning and inspections planned by rota instead of by use: the toilet by the entrance serviced as often as the one on a rarely visited floor.

The common denominator: someone is making each of these decisions today — just in the dark.

Room occupancy monitoring without a camera

The first association with presence measurement is a camera and image analysis — and with it a debate with the legal department and a distrustful team. There is a simpler way: passive infrared (PIR). A sensor with a Fresnel lens detects the movement of a heat source in its field of view and reports a binary fact: someone is here, or nobody is. No image, no sound, no identification of individuals — the sensor knows that someone is there, but not who. For analysing space utilisation, that is exactly enough.

Nextriv Sense Motion fits both required "senses" into a 5 × 5 cm cube weighing 40 g: a PIR detector with a 120° horizontal and 100° vertical field and a range of up to 6 m — one sensor covers a typical room or desk zone — and a 1–60,000 lx light sensor with a user-defined bright/dark threshold. That second parameter upgrades the automation from good to smart: supplementary lighting only makes sense when someone is in the room and it is actually dark. Mounting is double-sided tape or two screws, configuration — a tap of the phone (NFC), and the replaceable lithium battery runs for up to about 4 years. Installing one room takes minutes, a whole floor — one afternoon, with no wall chasing and no electrician.

What the data shows after the first month

The presence signals land in the Nextriv platform and build into a history you can view on dashboards — nearly 20 widget types are available, from simple status tiles to trend charts and tables of many sensors at once. After a few weeks the data starts answering questions that could previously only be argued about:

• which rooms are genuinely in demand, and which are "full" only in the calendar;
• at which hours the floor empties out — and whether the HVAC knows about it;
• whether the hot-desk zone is too small, or perhaps a third too large;
• which rooms can painlessly be given up, merged or repurposed.

You can take the data with you to a meeting with the board or the building owner: PDF reports with summaries and charts plus XLSX/CSV exports let you show zone occupancy for any period. The free plan stores a full year of measurement history — enough to compare seasons and see whether the September return to the office is a trend or a one-off spike.

Alerts: movement where nobody should be

The same sensors that measure space utilisation by day change roles after hours. A "movement after 22:00 in the archive" rule sends a notification through a channel that will genuinely reach its recipient: email, SMS, web push, Microsoft Teams, Discord or an audible in-app alarm. Every event gets a readable code and a status (active → acknowledged → resolved) with room for a comment, so a night incident can be properly reviewed in the morning, and if the person on duty fails to react, escalation hands it to the next person.

The platform also watches the installation itself: a sensor that goes quiet for twice its reporting interval automatically gets offline status — you learn about a dead battery from an alert, not from a hole in the data. The picture of "what happens in the building after hours" is worth completing with contact sensors on doors and windows — how that works is described in our piece on door and window contact sensors.

Occupancy plays best in a team

The "occupied/free" signal is valuable on its own, but it shows its full power combined with other measurements. Presence plus CO₂ concentration in a conference room is a ready answer to whether the ventilation keeps up with the people — we covered this in more depth in our article on CO₂ in conference rooms. Presence plus light measurement is lighting automation that wastes no energy on sunny days. And all of that data on one platform — with alerts, history and reports — is the foundation on which the whole smart building scenario is built.

From pilot to a whole floor

The sensors connect to the gateway over a long-range radio link — up to about 2 km in built-up areas and about 15 km in open terrain — so a single gateway in the server room or a utility room will serve the floors of an office building without running cables. A new sensor registers itself with the platform: auto-discovery usually takes 30 to 180 seconds, with no manual entering of identifiers.

The free plan is enough for a pilot: 10 sensors, a gateway, 5 alert rules and 365 days of history — enough to instrument the most contested rooms and return to the floor-space debate with charts instead of impressions. Plan details are in the pricing, and if you would rather see data from a real office first — book a demo.